The present invention relates to hand tools, and more particularly, the present invention relates to an apparatus used in dismantling the rivets of a bushed chain.
In dismantling a rivet of a bushed chain, a suitable tool shall be used. FIGS. 1, 2 and 3 illustrate two different apparatus for this purpose. In FIG. 1, the apparatus has a notch B on the bottom A of the base (10) thereof. Rotating the tommy screw (11) inwards in the top bolt hole (101) causes a rivet (12) to be moved out of a link (13) of a bushed chain. However, because of the arrangement of the notch B, dismantling a rivet (12) from one side-plate of a link (13) of a bushed chain may cause a rivet (12) to be completely disconnected from the two opposite side-plates of a link (13). Once a rivet has been removed from the two opposite side-plates of a link, it is very difficult to insert the rivet back into the holes on the two opposite side-plates of the link again. Further, because the side-plates of each link (13) of a UG chain respectively curve outwards, a link will be caused to deform when the rivet thereon is squeezed by the tommy screw (11) during a rivet dismantling process (see FIG. 2).
In order to eliminate the aforesaid problems, there is provided an another structure of apparatus, as shown in FIG. 3, for removing rivets from a bushed chain. In this structure, the base (20) has a bolt hole fastened with a hollow screw means (21). The hollow screw means (21) has a top edge (22) used in supporting the side-plates of the link (23) mounted thereon, so that the two opposite side-plates of the links (23) will not be caused to deform when the rivet (24) thereof is squeezed by the front pressure rod (26) of the tommy screw (25) which is inserted through the top bolt hole (201) of the base (20). However, once a rivet (24) has been pushed out of one side-plate of a link (23) by the tommy screw (25), the tommy screw (25) must be rotated outwards to move the front pressure rod (26) away from the rivet hole (241) on such side-plate, so that the rivet (24) can be moved out of the hole (211) of the hollow screw (21) permitting the chain to be taken out of the apparatus. Further, the top bolt hole (101;201) is formed on the base (10;20) at an offset location for screwing the tommy screw (11;25). Frequently screwing the tommy screw (11;25) in the top bolt hole (101;201) may damage the threads of the top bolt hole (101;201) easily. Although the top bolt hole (101;201) can be strengthened through a heat treating process, the threads of the top bolt hole (101;201) may be caused to deform easily during a heat treating process because the top bolt hole (101;201) provides different coefficient of contraction due to its uneven wall thickness. Therefore, this structure of chain rivet dismantling apparatus is not durable in use.